Solved by SP7618 TM Evaluation Board Manual • • • • • • • • • Very low dropout voltage, 100mV Accurate current regulation down to dropout voltage No external components Output current adjustable with 33.33mA/steps Power-saving shutdown mode of 12nA typical Fast turn-on (<50µS) Time Out function to protect the LED Thermal Shutdown Protection Space saving 2mm x 3mm 8 pin DFN package DESCRIPTION AND BOARD SCHEMATIC Figure 1. SP7618 Evaluation Board Schematic Diagram Dec 7-06 SP7618 Evaluation Board Manual Page 1 of 6 © 2006 Sipex Corporation The SP7618 Evaluation Board is designed to help the user evaluate the performance of the SP7618 for use as a single photo flash Luxeon LED Driver. The evaluation board is a completely assembled and tested surface mount board which provides easy probe access points to all SP7618 inputs and outputs so that the user can quickly connect and measure electrical characteristics and waveforms. The Evaluation Board schematic diagram is shown at Figure 1. The SP7618 is a linear low side constant current driver designed to drive high power LEDs from an input voltage rail. The driver acts as a high current source ensuring constant LED current for a range of input voltage. The SP7618 allows implementing the lowest cost LED driver for a variety of applications. Internal circuitry maintains the preset constant current output for a wide voltage range at the LED input. The LED current can be adjusted up to 1033mA with an external clock applied to the CTRL pin. The built-in thermal protection automatically stops LED current to prevent overheating. A timeout function serves as a fail safe, shutting down the output for currents greater than 266mA after 4 seconds of continuous operation if the enable input is not cycled. The part can be shutdown by using the EN pin or holding the CTRL pin low for more than 100µS. The evaluation board contains SP7618 driver (U2) with one Luxeon Flash LED as a load (D1) and pulse generator. The pulse generator (U1, U4, and U5) is used to provide a pulse sequence to the driver’s CTRL and EN pins to set LED current and turn the driver on/off. The number of pulses that determines LED current may be set by 5-bit dipswitch (U3) using binary code. The number of pulses depend on switch position is shown on Table 1. . USING THE EVALUATION BOARD 1) Selecting the LED current LED current can be adjusted up to 1033mA with a series of pulses applied to the CTRL pin. Each pulse increases nd the output current in steps of 33.33mA. The maximum number of the pulses is 31. The 32 and following pulses are ignored. The number of pulses depends on the switch position as shown on Table 1, which is on the next page. Dec 7-06 SP7618 Evaluation Board Manual Page 2 of 6 © 2006 Sipex Corporation . Number Position of DIP-Switches of pulses 1 2 3 4 5 1 + + + + 2 + + + + 3 + + + 4 + + + + 5 + + + 6 + + + 7 + + 8 + + + + 9 + + + 10 + + + 11 + + 12 + + + 13 + + 14 + + 15 + 16 + + + + 17 + + + 18 + + + 19 + + 20 + + + 21 + + 22 + + 23 + 24 + + + 25 + + 26 + + 27 + 28 + + 29 + 30 + 31 Table 1. Code Table Note: “+”- this switch is in ON position If all switches are in ON position the number of pulses is 256. 2) Powering Up the SP7618 Circuit The SP7618 Evaluation Board can be powered from a 4.5V power supply or from 3 alkaline cells. Connect 4.5V source pin with short lead directly to the “Vin” and -4.5V/GND pin to the “GND” posts. Install shunt S1 to short pins 2-3 (The Evaluation board is delivered by default with shunt in this position. If shunt S1 isn’t installed or short pins 1-2 the driver SP7618 is disabled). Push the button S2. Driver (U2) will provide to the LED current in respect to dip-switch (U3) position. If the output current is higher than 266mA (8 pulses), the driver will turn off after 4s to prevent LED damage. Every push on button S2 turns the driver off/on and sends the CTRL pin a new pulse sequence depending on the dip-switch position. Disconnect Evaluation board from power supply to turn it off. Dec 7-06 SP7618 Evaluation Board Manual Page 3 of 6 © 2006 Sipex Corporation LED Current, m A 1200 1000 800 600 400 200 0 0 5 10 15 20 25 30 35 Pulses # Measured Value Calculated Value Graph 1. LED Current vs. number of input pulses Relative Error, % 6 5 4 3 2 1 0 0 5 10 15 20 25 30 35 Pulses # Graph 2. LED Current Relative Error vs. number of input pulses 1200 1000 Iled, mA 800 600 400 200 0 0 0.5 1 1.5 2 2.5 3 3.5 Vled, V 3 pulses 7 pulses 15 pulses 31 pulses Graph 3. Load regulation at Vin = 5.5V 1200 1000 Iled, mA 800 600 400 200 0 0 100 200 300 400 500 600 700 Vled, V 25C 85C 0 0 Graph 4. Load regulation at 25 C and 85 C Dec 7-06 SP7618 Evaluation Board Manual Page 4 of 6 © 2006 Sipex Corporation EVALUATION BOARD LAYOUT Figure 2. SP7618 Evaluation Board Layout top and bottom side Count Reference Designator Value Description 2 2 5 1 1 1 1 1 1 7 5 1 1 1 1 1 1 1 2 C1, C2 C3 C4, C5, C6, C7, C9 C8 D1 D2 P1 P2 P3 R1, R2, R3, R4, R5, R13, R14 R6, R8, R9, R10, R12 R7 R11 S1 S2 U1 U2 U3 U4, U5 0.1uF 0.01uF 1000pF 4700pF 0603ZC104MAT AVX 06033C103MAT2A AVX 06033C102MAT2A AVX 06033C472MAT2A AVX LXCL-PWF1 Lumileds BAT42WS Diodes Inc 1001-0-15-01-30-02-04-0 Mill-Max 1001-0-15-01-30-02-04-0 Mill-Max 1001-0-15-01-30-02-04-0 Mill-Max CRCW0603104J Vishay CRCW0603102J Vishay CRCW0603105J Vishay CRCW060347RJ Vishay Header 42375-22-28-4033 Molex 7914 G-002-000E Bourns CD74HC40103M SP7618 Sipex 5-bit DIP Switch 74VHC00MTC Fairchild GND EN Vin 100k 10k 1M 47 Table 2. SP7618EB List of Materials Dec 7-06 SP7618 Evaluation Board Manual Page 5 of 6 © 2006 Sipex Corporation ORDERING INFORMATION Model Temperature Range Package Type SP7618EB................................................... -40°C to +85°C........................................ SP7618 Evaluation Board SP7618ER-L/TR...........................................-40°C to +85°C..............................Lead Free 8-pin DFN (2 x 3 mm) /TR = Tape and Reel Pack quantity is 3000 for DFN. For further assistance: Email: WWW Support page: Live Technical Chat: Sipex Application Notes: [email protected] http://www.sipex.com/content.aspx?p=support http://www.geolink-group.com/sipex/ http://www.sipex.com/applicationNotes.aspx Solved by TM Sipex Corporation Headquarters and Sales Office 233 South Hillview Drive Milpitas, CA95035 tel: (408) 934-7500 fax: (408) 935-7600 Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights nor the rights of others. Dec 7-06 SP7618 Evaluation Board Manual Page 6 of 6 © 2006 Sipex Corporation